China
Africa
Explore chapters and articles related to this topic
Dietary Influence on Muscle Protein Synthesis and Hypertrophy
Published in Peter M. Tiidus, Rebecca E. K. MacPherson, Paul J. LeBlanc, Andrea R. Josse, The Routledge Handbook on Biochemistry of Exercise, 2020
James McKendry, Stuart M. Phillips
Since the early stable isotopic tracer studies (89), a considerable body of knowledge has accumulated examining nutritional influences on MPS, and protein nutrition is the most comprehensively studied. Dietary protein comprises a varying portion of daily macronutrient intake (usually 15–20% of total energy intake) and is essential for muscle function and growth. Following protein ingestion, the ensuing hyperaminoacidemia leads to an influx of AAs into muscle cells and a stimulation of MPS, the magnitude and duration of which can be influenced by a variety of factors (i.e., the dose, AA composition, source, distribution, and co-ingestion with other macronutrients).
Immunotherapy of the BB Rat *
Published in George S. Eisenbarth, Immunotherapy of Diabetes and Selected Autoimmune Diseases, 2019
John P. Mordes, Eugene S. Handler, Dina Burstein, Dale L. Greiner, Aldo A. Rossini
The clinical appearance of disease in the diabetes prone (DP) BB rat is similar to that observed in children experiencing the acute onset of IDDM.4 It is characterized by the rapid onset of hyperglycemia, ketoacidosis, hyperglucagonemia, and hyperaminoacidemia. The disease appears with equal frequency, typically 40 to 70%, in both male and female animals of normal body habitus, all of whom become dependent on exogenous insulin for survival. Mean age at onset is about 90 d. In addition, it appears that long-term diabetic rats develop neural, retinal, and renal complications of their disease.
Protein and amino acids
Published in Jay R Hoffman, Dietary Supplementation in Sport and Exercise, 2019
Proteins display different absorption kinetics that can impact plasma amino acid availability. As a result, hyperaminoacidemia can increase MPS. Proteins can have different constituent amino acids which may involve a greater amount of EAAs, especially leucine. The composition or dose of EAAs provided, rather than the bioavailability, may be a primary determining factor towards MPS in response to protein intake. There is a dose-dependency and transiency regarding the anabolic response to protein and EAAs. The maximal anabolic response appears to occur with an intake between 20–40 grams (0.3–0.6 g/kg body mass) of high-quality protein with each meal. Doses of EAAs beyond those utilized as MPS substrates, and in other tissues, are directed through oxidation and urea synthesis in the liver with the remaining carbon skeletons being made available for gluconeogenesis.
Laboratory testing for mitochondrial diseases: biomarkers for diagnosis and follow-up
Published in Critical Reviews in Clinical Laboratory Sciences, 2023
Abraham J. Paredes-Fuentes, Clara Oliva, Roser Urreizti, Delia Yubero, Rafael Artuch
Lactate, pyruvate, and alanine are in biochemical balance due to the activity of the enzymes, alanine aminotransferase, and lactate dehydrogenase (Figure 1). Thus, increased plasma alanine levels are frequently found in individuals with chronic lactate elevations [36]. Quantitative plasma amino acid analyses are commonly performed when evaluating patients with possible mitochondrial metabolism disorders. Elevations in several amino acids, including alanine, lysine, glycine, proline, and threonine [28] (Table 1), occur due to altered redox states and other pathomechanisms secondary to mitochondrial respiratory chain (MRC) dysfunction (Figures 1 and 2). Plasma alanine levels greater than 450 µmol/L are suggestive of mitochondrial dysfunction although they are nonspecific and not diagnostic. Moreover, the presence of normal alanine concentrations does not exclude mitochondrial dysfunction [22]. Like other biomarkers of MDs, the sensitivity and specificity of elevated alanine levels are low, as they may be elevated only during times of stress or worsening clinical situation. Amino acid analysis can be useful when alanine elevations are present in both plasma and CSF, and especially when hyperalaninemia is present in a fasting sample. The advantage of incorporating alanine measurements in evaluations of MDs is the relative resistance of this amino acid to artifacts that may result from improper specimen collection and handling. However, analysis of postprandial samples must be avoided, as they result in generalized hyperaminoacidemia [27]. Other amino acid levels, e.g. arginine and citrulline, may also be abnormal (Table 1).
Glucagon receptor signalling – backwards and forwards
Published in Expert Opinion on Investigational Drugs, 2018
Tongzhi Wu, Christopher K. Rayner, Chinmay S. Marathe, Karen L. Jones, Michael Horowitz
Glucagon also promotes the catabolism of lipids and amino acids. This concept was initially supported by observations in experimental animals during chronic administration of glucagon, and has now been validated in humans receiving exogenous glucagon ‘replacement’ during pancreatic clamp studies [13], or patients with a glucagonoma [14]. The opposite effects are evident in the setting of inactivating GCGr mutations, or after administration of GCGr antagonists. There is also recent evidence that hyperaminoacidemia may modulate α-cell activity reciprocally by a feedback loop between the liver and pancreas [14].